Hemiplegic migraine: one-sided weakness, and why the first episode is always an emergency

Short answer

If you or someone near you suddenly has weakness or numbness on one side of the body, a drooping face, slurred speech or trouble seeing, call 911 now — do not wait to find out whether it is a migraine. These are stroke signs, and a stroke cannot be told apart from hemiplegic migraine at home (8, 3).

Hemiplegic migraine is a rare type of migraine with aura in which the aura includes temporary, fully reversible weakness on one side of the body, together with visual, sensory or speech symptoms (1). The weakness usually lasts less than 72 hours, although in some people it lasts for weeks (1). A Danish study estimated that it affects about 1 in 10,000 people (3). It can run in families (familial hemiplegic migraine, linked to genes such as CACNA1A, ATP1A2 and SCN1A) or appear without a family history (sporadic) (2).

If you have been through an episode like this, you are not overreacting and you are not imagining how frightening it was: losing strength on one side of your body is serious until a doctor proves otherwise, and getting help fast is exactly the right response.

Note: This article explains research. It is not medical advice and it does not diagnose migraine or stroke. Call 911 for sudden one-sided weakness or numbness, face drooping, slurred speech, vision changes, loss of balance or a sudden severe headache (8). This guide is published by Welltory, which makes one of the apps mentioned.

If you live with migraine and want to work through it with other women who get it, Welltory runs a paid peer-support program: join Migraine Lab here (what Migraine Lab is, who it is for and what it costs). It is education and peer support, not medical care.

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What is hemiplegic migraine?

"Hemi" means half and "plegic" means paralysis. In practice, most attacks cause weakness rather than full paralysis — ICHD-3 notes this directly (1). In the International Classification of Headache Disorders (ICHD-3), hemiplegic migraine is code 1.2.3, a subtype of migraine with aura. To meet the definition, the aura must include both (1):

1. fully reversible motor weakness; and

2. fully reversible visual, sensory and/or speech or language symptoms.

The key word is reversible: the weakness goes away completely. That is also why it is so dangerous to guess. A stroke can start in exactly the same way, and in a stroke the damage depends on how fast treatment begins.

There are two main forms (2, 3):

• Familial hemiplegic migraine (FHM): at least one first- or second-degree relative (parent, child, sibling, grandparent, aunt or uncle) has had the same kind of attacks.

• Sporadic hemiplegic migraine (SHM): the same attacks, but no relative is affected.

Hemiplegic migraine sits inside the wider migraine family. Its underlying process is close to that of typical migraine with aura, but appears with a lower threshold and greater severity (4). For a general overview of migraine types, see our guide to migraine.

Hemiplegic migraine or stroke? Why you call 911 first

This is the most important section of this article.

You cannot tell hemiplegic migraine from a stroke by how it feels. Cleveland Clinic says hemiplegic migraine itself is not an emergency, but it can mimic a stroke, and you should call 911 right away for stroke-like symptoms — and contact emergency services if you are unsure which one you are having (3). Even doctors need an examination and brain imaging to tell them apart.

Use CDC's B.E. F.A.S.T. check (8):

What to do, step by step:

1. Call 911 — do not drive to the hospital or let someone else drive you; paramedics can start care on the way (8).

2. Note the time the symptoms started. It helps doctors decide on the best treatment (8).

3. Tell the team if you have a diagnosis of hemiplegic migraine, and what medicines you take.

4. Do not take migraine medicine "to see if it helps" before you have been assessed. Some migraine medicines are not suitable for people with hemiplegic migraine or stroke (see the treatment section).

What if I already have a diagnosis? Agree a written emergency plan with your neurologist: which symptoms are your usual pattern, and which mean going to the emergency department every time. Ask specifically about attacks that feel different from your usual ones — longer, on the other side, with new symptoms, or with confusion or drowsiness.

NHS lists these as reasons to call emergency services during a migraine: a sudden, extremely painful headache; problems speaking or remembering things; vision loss or blurred or double vision; drowsiness or confusion; a seizure; a very high temperature with signs of meningitis; inability to move or weakness in the arms or legs on one side of the body or one side of the face; and a recent head injury (9).

Hemiplegic migraine symptoms

An attack usually begins with aura. The weakness typically starts during the aura phase, often along with other aura symptoms (3). Cleveland Clinic lists (3):

• weakness on one side of the body — face, arm and/or leg;

• vision changes: blind spots, flashing lights, zigzag patterns or double vision;

• numbness or tingling in the face, arms and legs;

• difficulty speaking;

• fatigue and confusion.

A headache usually follows, but not always right away. In familial hemiplegic migraine, ICHD-3 notes that headache almost always occurs and that brainstem symptoms — such as dizziness, double vision or unsteadiness — are very often present alongside typical aura (2).

Rarer and more serious features in familial forms include disturbed consciousness, sometimes as deep as coma, confusion, fever and inflammation markers in the spinal fluid (2). In about half of families with FHM, a slowly progressive problem with coordination (cerebellar ataxia) develops, independent of the attacks (2). Some people also have intellectual disability (4).

A tip on describing it. ICHD-3 notes that it may be difficult to tell weakness from sensory loss (1). A numb, "dead" arm can feel weak even when the muscles work. Try to notice: could you lift your arm and grip, or did it just feel strange? Your doctor will ask.

How long does a hemiplegic migraine last?

Longer than typical aura. ICHD-3 allows ordinary aura symptoms to last 5 to 60 minutes each, but motor symptoms up to 72 hours (12), and in some patients motor weakness persists for weeks (1).

• ICHD-3 — Motor symptoms generally last less than 72 hours; in some patients, weeks (1)

• Cleveland Clinic — Symptoms can last from an hour to a few days, rarely up to four weeks, and usually resolve completely (3)

• Di Stefano et al., 2020 review — Motor symptoms usually last less than 72 hours; long-lasting auras may need hospital care (4)

Because of these long auras, NHS advice to get urgent help when aura lasts longer than 1 hour applies with extra force (9). If weakness is still there after your usual pattern, or you have no diagnosis yet, go to the emergency department.

Work out your early warning signs with women who get it

Welltory Migraine Lab is a paid, moderated online community for women 18 to 65 living with migraine. Opens December 1, 2026. Peer support and education, not medical care.

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What causes hemiplegic migraine? Familial and sporadic types

Hemiplegic migraine is closely tied to genes that control how ions — calcium, sodium and potassium — move in and out of nerve and brain support cells. ICHD-3 lists three established familial subtypes (2):

Cleveland Clinic also lists PRRT2 (3). The familial form is inherited in an autosomal dominant way, meaning one changed copy of the gene can be enough (4). These mutations are thought to make the brain more excitable and more prone to cortical spreading depression, the slow electrical wave that is thought to coincide with aura (6).

Genes do not explain every case. About 75% of people with hemiplegic migraine test negative for mutations in the three main genes, which means other genes are likely involved (5). A negative genetic test therefore does not rule out the diagnosis.

What triggers an attack? Cleveland Clinic lists stress, sleep changes, physical exertion, head trauma, bright lights, and certain foods or missed meals; some attacks have started after a cerebral angiogram, an imaging test of brain blood vessels (3). ICHD-3 notes that even mild head trauma can trigger attacks in the familial form (2). If you have hemiplegic migraine, mention it before any procedure on the head or brain blood vessels, and to coaches if you play contact sports. For how triggers work in migraine generally, see migraine triggers.

What is a complex migraine?

"Complex migraine" is an informal term you may hear in an emergency department or read in an old discharge note. It is not an official diagnosis and is not recognized by the International Headache Society (10). In a National Headache Foundation discussion, headache specialist Dr. Fred Cohen described it as an umbrella term some providers use for less typical forms of migraine with aura — mainly hemiplegic migraine, migraine with brainstem aura and retinal migraine (10).

Why the label matters: these forms are treated differently from common migraine. In the same discussion, Dr. Cohen said that for hemiplegic, brainstem and retinal migraine, specialists typically do not treat with triptans (10). If someone told you that you have "complex migraine," ask which specific type it is.

How is hemiplegic migraine diagnosed?

The diagnosis is clinical — based on your history and examination — with genetic testing used for confirmation where possible (4). The first job is always to rule out stroke and other causes. According to Cleveland Clinic, doctors may use (3):

1. a physical and neurological exam;

2. a CT scan and/or MRI of the brain, to look for stroke, bleeding or other changes;

3. a lumbar puncture (spinal tap), to examine the spinal fluid;

4. an EEG, which records the brain's electrical activity, to look for seizures;

5. genetic testing.

The list of conditions to exclude is broad — it includes other types of migraine and any condition that causes temporary neurological symptoms (4). Hemiplegic migraine can be mistaken for epilepsy and treated as such, without success (2). Usually the diagnosis becomes clear only after more than one episode with full recovery and normal tests — which is why the first episode is always treated as a possible stroke.

Who to see: a neurologist, ideally a headache specialist. If a relative has similar attacks, a genetic counselor can help you decide on testing for yourself or your children.

Hemiplegic migraine treatment: what doctors consider

Because hemiplegic migraine is rare, there are no randomized controlled trials; the evidence comes from small studies (4). Treatment is individual and should be led by a neurologist. This section explains the options so you can discuss them — it is not a plan to follow on your own.

Avoiding triggers and planning for long auras. Management relies on controlling triggering factors and, when auras last a long time, sometimes on hospital care (4).

Preventive medicines. Cleveland Clinic lists several classes that doctors may use (3):

• certain antidepressants (tricyclics, SNRIs);

• beta-blockers or calcium channel blockers;

• anti-seizure medicines;

• CGRP-targeting medicines and/or botulinum toxin, when appropriate.

Which one fits — and at what dose — depends on your attacks, your other conditions and side effects. That is a decision for you and your neurologist.

Triptans: a known caution. Triptans are a common class of migraine medicine. The FDA prescribing information for sumatriptan (Imitrex) lists a history of hemiplegic or basilar migraine as a contraindication, alongside a history of stroke or TIA, "because these patients are at a higher risk of stroke" (7). If you have hemiplegic migraine, tell every prescriber, pharmacist and emergency team. Do not start or stop any migraine medicine without talking to your doctor.

Pain relief. Cleveland Clinic suggests asking your provider whether anti-inflammatory painkillers (NSAIDs) are safe for you (3).

For a broader overview of migraine medicines and how they work, see our guide to migraine treatment — and remember that not everything there suits hemiplegic migraine.

Hemiplegic migraine and stroke risk: what is known

People often ask whether hemiplegic migraine itself causes strokes. The honest answer is that the data are limited, because the condition is rare. What we know:

• Migraine with visual aura is linked with a higher risk of ischemic stroke in women under 50, and the risk rises further in those who smoke and use oral contraceptives (11). Most of this research is on visual aura; the risk for other aura types needs more study (11).

• The risk is small but real, and a specialist can look at other factors — smoking, estrogen-based birth control and high blood pressure — according to Dr. Cohen (10).

• The FDA label for sumatriptan treats hemiplegic migraine as a higher-stroke-risk group, which is why triptans are contraindicated (7).

Practical takeaways: if you have hemiplegic migraine, tell whoever prescribes your contraception or hormone therapy, ask about blood pressure checks, and talk about quitting smoking if you smoke. For a broader look at stroke under 50, see our guide to stroke in young adults.

Living with hemiplegic migraine: the questions people ask next

Is hemiplegic migraine dangerous?

The weakness usually resolves completely (3), but attacks can be severe: in familial forms they can include confusion, reduced consciousness or, rarely, coma (2). The biggest everyday danger is mistaking a stroke for "just my migraine." Any attack that differs from your usual pattern needs emergency care.

Can you die from hemiplegic migraine?

Hemiplegic migraine itself is not usually life-threatening, and most attacks end with full recovery (3). The real risk is a missed stroke or a severe attack with reduced consciousness, which needs hospital care (2, 4). That is why a clear emergency plan matters.

Can hemiplegic migraine cause permanent damage?

By definition, the weakness in hemiplegic migraine is fully reversible (1), and symptoms usually resolve completely (3). In about half of families with FHM, a slowly progressive coordination problem (cerebellar ataxia) develops independently of attacks (2). Ask your neurologist about your own risk.

How rare is hemiplegic migraine?

Very rare. A Danish study estimated about 1 in 10,000 people (3). Common migraine is far more frequent, which is one reason a specialist opinion helps.

Can you drive with hemiplegic migraine?

Never drive during an attack or while any weakness, numbness, vision or speech symptoms remain. If attacks come without warning, ask your neurologist whether it is safe for you to drive and check your state's rules.

Is hemiplegic migraine a disability?

It can be: long auras, unpredictable attacks and recovery time can affect work and daily life. Whether it qualifies for accommodations or benefits depends on how it limits you and on local rules. A diary of attacks, hospital visits and missed work helps any request. For decisions about returning to work, see should I go to work the day after a migraine?

Before you blame yourself

After an attack that ended in an emergency department and "only" a migraine diagnosis, many people feel embarrassed for calling 911. Please do not. With one-sided weakness, calling was correct every time: even doctors cannot tell a stroke from hemiplegic migraine without tests. Hemiplegic migraine is also often genetic, not a result of something you did. Before you blame yourself, look at what your body recorded in the days before an attack: sleep changes, a hard physical effort, a stressful week, a missed meal — all known triggers (3). Choose one lever, such as regular sleep and wake times, keep it for 2 weeks, and bring what you notice to your neurologist.

When to see a doctor

Call 911 for sudden one-sided weakness or numbness, face drooping, slurred speech, trouble seeing, loss of balance or a sudden severe headache (8) — especially the first time, or whenever an attack is different from your usual ones. NHS adds a seizure, drowsiness or confusion, a very high temperature with signs of meningitis, and a headache after a recent head injury (9).

Get urgent advice if aura symptoms last longer than 1 hour, if a migraine attack lasts longer than 72 hours, or if you are pregnant or have just had a baby (9).

See your doctor or neurologist if attacks are becoming more frequent or severe, happen more than once a week or are hard to control (9), if a relative has similar attacks, or before starting any new migraine medicine or hormonal contraception.

How to bring this up with your doctor

• Bring a record of each attack: date, start and end time of each symptom, which side, whether you could grip and lift, speech and vision changes, headache, and what came before.

• Bring discharge notes and scan reports from any emergency visit.

• Share family history: has anyone in your family had attacks with weakness, "strokes" that fully recovered, seizures or coordination problems?

• Ask by name: "Is this hemiplegic migraine, familial or sporadic? Should I have genetic testing?" "Which migraine medicines should I avoid?" "Is my birth control or hormone therapy suitable?"

• Ask for a written emergency plan you can show paramedics.

• If you feel dismissed, say: "I had weakness on one side of my body. I would like a referral to a neurologist or a headache specialist."

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How Welltory helps — and what it cannot do

What it cannot do. Welltory is a general wellness product, not a medical device. It cannot detect a stroke or tell it from hemiplegic migraine, it does not measure anything in the brain, it does not diagnose migraine and it cannot predict an attack. If you have one-sided weakness, call 911 — do not open an app. Our review of whether a smartwatch can predict a migraine explains why no wearable can yet.

What it can do is help you collect the context around your attacks once you are safe:

• Tag what happened. If you use an iPhone with an Apple Watch or Oura ring, the Today screen flags stress stretches and asks "What happened?" — tap a suggested tag, type a few words or just talk, later, when you have recovered: "left arm weak 3 hours," "short night," "hard workout," "skipped lunch." Those tags are what you look back on with your neurologist.

• Look at the 1–3 days before. Sleep, resting heart rate and activity come from your watch or ring; you can connect Apple Health, Health Connect and other sources. Sleep changes and physical exertion are known triggers (3), so a run of short nights or heavy training before attacks is worth discussing.

• A quick heart rate and HRV reading with your phone camera. It is a spot reading, not continuous monitoring, and it is not a check for stroke; follow the measurement guide and the tips for accurate HRV readings.

• Looking back at patterns. On iOS, My Patterns shows how your measurements relate to what you log.

• A record for your neurologist. Your tagged attacks and notes build a personal log; you can export your data as a CSV file from the web app. Patterns are links to discuss with your doctor, not proof of a trigger. For what else to write down, see our migraine headache diary guide.

Working this out with other women. Welltory Migraine Lab is a paid, moderated online community for women aged 18 to 65 living with migraine; you do not need a formal diagnosis to join. It opens on December 1, 2026; you can book your place now, and your paid period starts on the opening day. Members get a personal strategy built on their own data, a community of women with similar symptoms, and a medical board that explains what is happening in the body. It is education and peer support, not medical care, and it does not replace your clinician or your emergency plan. Join Migraine Lab or read what Migraine Lab is, who it is for and what it costs.

How we made it

We based this article on the International Classification of Headache Disorders (ICHD-3), reviews in the Journal of Neurology, Neurosurgery & Psychiatry, Genes, The Journal of Headache and Pain and the Journal of Stroke and Cerebrovascular Diseases, the FDA prescribing information for sumatriptan, Cleveland Clinic patient guidance, a National Headache Foundation specialist discussion, CDC stroke warning signs and NHS guidance on when to seek care. Every number was checked against the source we cite on November 10, 2026. Search questions came from what people in the United States most often ask about hemiplegic and complex migraine. For the product section, we checked every function against the Welltory Help Center on November 10, 2026.

Made with AI tools, then edited and fact-checked by the Welltory team. See our Editorial & AI policy.

Jane Smorodnikova, co-founder of Welltory, built the methodology behind how we read physiological data.

Written by Tatsiana Yashyna.

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